Does this beginning sound interesting?

It sounds interesting, but you jump into the story too quickly. Make sure to give your readers some background before you really get into the story. For example, what is a Cryotorian? We can determine that they're aliens, but why are they on earth? How did they get there? Maybe you could have Katie daydreaming in class, thinking about the past, the history between humans and Cryotorians. Then the teacher's voice could snap her out of her daydream, and we'd all be on the same page. The writing is excellent though, and the story sounds really good! Good luck!